Field of the Invention
The present invention relates to transmission resource block constraint and power reduction.
Related Art
3GPP (3rd Generation Partnership Project) LTE (long term evolution), an advanced version of UMTS (Universal Mobile Telecommunications System), is introduced in 3GPP release 8.
3GPP LTE adopts OFDMA (orthogonal frequency division multiple access) on downlink and SC-FDMA (Single Carrier-frequency division multiple access) on uplink. Knowledge of OFDM comes first for understanding OFDMA. OFDM may attenuate inter-slice boundary interference with low complexity and thus comes in use. OFDM converts data input in series into N parallel data items and transmits the converted data items on N orthogonal subcarriers. A subcarrier maintains frequency orthogonality. Meanwhile, OFDMA refers to a multiple access scheme that independently provides some of subcarriers available in a system adopting OFDM as its modulation scheme to each user, thus implementing multiple access.
FIG. 1 illustrates a 3GPP LTE wireless communication system.
Referring to FIG. 1, an LTE wireless communication system 10 includes at least one base station (BS) (which is referred to as eNodeB in LTE) 11 and a user equipment 12.
Each base station 11 provides a communication service in particular geographical areas 15a, 15b, and 15c. In this case, communication from the base station to the user equipment is denoted downlink (DL), and communication from the user equipment to the base station is denoted uplink (UL).
In case base stations are presented by a number of service providers in the geographical areas 15a, 15b, and 15c, interference may occur therebetween.
For excluding such interference, each service provider may offer a service with a different frequency band.
However, in case the frequency bands from the service providers are positioned adjacent to each other, the problem of interference still remains. Such interference issue may be addressed by reducing transmission power or restricting the amount of reference blocks (RBs) to substantially increase the frequency interval between neighbor bands. However, the reduced transmission power or restricted transmission resource blocks may result in a reduction in service coverage. Accordingly, a need exists for a method for reducing transmission power or transmission reference blocks to a proper level without causing the interference issue.